Test on Python 2.7 and 3.5-3.9. Release on 3.9.

Author: jaraco

.github/workflows/main.yml

@@ -6,7 +6,7 @@ jobs:
   test:
     strategy:
       matrix:
-        python: [3.6, 3.7, 3.8]
+        python: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
@@ -33,7 +33,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v1
         with:
-          python-version: 3.8
+          python-version: 3.9
       - name: Install tox
         run: |
           python -m pip install tox